Alloy



' 25 able to be used Patented Apr. 14, 1931 PATENT OFFICE ALBERT n MAOFARLAND, or NEWARK.

NEW JERSEY, ASSIGNOR TO SIBIAN WIRE AND CONTACT COMPANY, OF NEWARK, NEW JERsEY A CORPORATION OF DEAWABE ALLOY No Drawing.

This invention relates to alloys for the manufacture of resilient wire, and particularly to an alloy which may be used in the manufacture of wire to resiliently support thg ends of the filament in a radio vacuum tu e.

A resilient support for the filaments of vacuum tubes must be made ofsuch material I I that it will maintain its resiliency under considerable heat and'at the same time be free of occluded gases and subject to a minimum of deterioration during the operation of the tube. Such a wire must also be readily workable so thatit can be bent up into proper shape, such as a hook for supporting the en of the filament.

Heretofore it has been difficult to find a wire which would answer all of'the requirements, inasmuch as the wirewas either too brittle and considerable. waste was encountered dueto breakage of the wire when bending it into the proper form, or the wire was not resilient enough to maintain the proper tension on the filament, or it was not suitin a vacuum tube for other reasons, such as the evolution of gases which might interfere with the operation of the tube.

vention to provide readily worked and maintain its resiliency under temperatures and at the same occluded gases.

Other objects of the invention will be apparent as the description thereof proceeds.

The alloy comprising the invention is composed of molybdenum, tungsten and chromium, the latter two being in relatively small proportions. In manufacturing the win out of this alloy, I first take a quantity of pow- "-dered molybdenum and add to it a small percentage of tungsten and about one per cent of chromium, all of these metals being in powdered form, or I may mix the first two as reducible compounds,-reducing them together before adding the chromium which forms a more intimate mixture. The three metals are then thoroughly mixed, as in a ball mill, until they are evenly distr buted is therefore one of the objects of the inan alloy which may be drawn and which will relatively high time be free 0 f used, but I Application filed December 4, 1928. Serial No. 823,783.

throughout the mass, whereupon the metal thus formed is placed in a die and put into a hydraulic press Where it is subjected to a pres sure of some forty tons.. This compresses the metal into an ingot or slug which resembles a solid bar of metal but which is more or less brittle, due to the fact that metal are only physically bonded together. The slug is then placed in a furnace and a high current of preferably over 700 amperes is run through it, raising the temperature to a considerable degree which sinters the metals so that adjacent corners. of the particles flow slightly into each other, causing greater add hercnce of the particles, while still they do not completely flow into each other to form a solid metal slug.

The slug, having been sintered, is now free to be worked, and I pass it through several swaging machines to successively decrease its diameter and increase its length, maintaining a high temperature at the same time, and when the length becomes such that it is inconvenient to swage it, I pass the metal through a succession of drawing dies until the diameter has been decreased to the size of wire desired, which is somewhere in the neighborhood of ten thousandths of an inch. The wire, of course, is heated before it passes through each die to maintain it at red heat during the drawing operation.

Any desired amount of tungsten may be have found that good results an obtained by using in the neighborhood of ter per cent of the whole in the first mixing ste; wherein molybdenum and tungsten, are re duced, althoughl do not desire to limit thl amount to this figure. The amount of chro' mium added depends considerably upon thi size desired for the finished wire. I hav found that one per cent of the entire mixtur permits drawing of very fine wires,'while i the percentage of chromium is increased i becomes more and more difiicult to draw th wire down to the smaller sizes. The chro mium may be added, therefore, in amount depending on the size desired, for ordinar requirements not exceeding five per cent.

The wire thus formed'is resilient and ver; hard but still may be bent "about small rad Ila the particles of and otherwise worked without breaking it. The Wire is readily adapted to be used in vacuum tubes, inasmuch as it does not occlude gases or tend to deteriorate in the normal mention of the tube.

Having thus described the invention, what desire to secure by Letters Patent is:

1. An alloy consisting of ninety per cent by veight of molybdenum, nine per cent by veight of tungsten, and one per cent by veight of chromium.

2. An alloy consisting of approximately 0% by weight of molybdenum, 5 to 9% by veight of tungsten, and 5 to 1% by weight f chromium.

In testimony whereof, I aiiix my signature.

ALBERT E. MACFARLAND. 

